Hi Kate:
Breathing of any kind is always best especially when compared to no breathing at all!
Master Lin says he always does the reverse breathing. There are many different kinds of QiGong breathing techniques and some of these masters go to great lengths to teach all these breathing styles and methods. Embryonic breathing was always one of my favorite ones!
Master Lin does not get bogged down with all the esoteric breathing debates. It is a great example where keeping it simple really is best. The most important thing is nice long deep breaths and visualizing all that good chi/energy/prahna coming into your physical body through your skin all over.
When you get deeper into your meditations you will find that breathing for some people can get in the way of letting you leave your body behind. I think this is why so much emphasis is given to the breathing.
I think Master Lin wants you to try and do the reverse breathing as much as possible as it is a nice reminder to yourself throughout the day that you are trying to change your old patterns and ways of doing things that really have not been effective. By reverse breathing you feel stronger, are more centered and instantly in each moment take charge of your life. Making the yin-yang water, not eating before or after QiGong practice, putting your tongue on the roof of your mouth.... all these things are ways to remind yourself that you are indeed changing and growing spritually and storing up energy, loosening those blockages and letting the chi flow. Think of it as a game to do these things and in time you'll be catching yourself reverse breathing as the day goes along and in a year or two you'll be doing it all the time. Another thing to do all the time (except when you are talking or eating!) is to leave your tongue on the roof of your mouth to keep that front and back channel connected.
Finally see if you can pat your stomach and jump up and down at the same time and you'll be a master by the third moon! I'm just kidding about this last paragraph you know.
Cheers,
Agent B